Counting Atoms & Conservation of Mass

Front

What is the law of conservation of mass?

Back

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Front

If you add 0.25 grams of baking soda to 5 grams of water, what will be the mass of the final solution?

Back

5.25 grams.

Front

What does a subscript in a chemical formula indicate?

Back

A subscript indicates the number of atoms of the element in the molecule.

Front

How many atoms of an element are present if there is no subscript in its chemical formula?

Back

Only 1 atom.

Front

What is a balanced chemical equation?

Back

A balanced chemical equation has the same number of each type of atom on both sides of the equation.

Front

Is the equation H2 + O2 --> H2O balanced or unbalanced?

Back

Unbalanced.

Front

What is the significance of balancing chemical equations?

Back

Balancing chemical equations ensures that the law of conservation of mass is upheld, showing that matter is conserved in a reaction.

Front

What is the balanced equation for the reaction of sodium and water?

Back

2Na + 2H2O --> 2NaOH + H2.

Front

What is the total mass of reactants in a chemical reaction if the products have a mass of 10 grams?

Back

10 grams, according to the law of conservation of mass.

Front

What is the difference between a coefficient and a subscript in a chemical equation?

Back

A coefficient indicates the number of molecules, while a subscript indicates the number of atoms in a molecule.